Does 650B reduce toe overlap?

[NHAero]

Would please say more about your sense that 42mm is the lower limit on 650B?

Originally Posted by happycampyer

The thing is, once you step down to 650b, a 42mm tire is as narrow as I would go unless you were building a wide-tire aero road bike. 42mm sounds wide, but I would compare it to a 700c wheel with 32mm tires.

Either way, yes, a bike with 650b wheels with either 38 or 42mm tires and fenders should have less toe overap than a 700c wheeled bike with fenders. I'll measure the pedal-to-wheel distances on my all-road bikes and let you know what the differences are.

[Pastashop]

I’ve one bike designed for 650x38xFenders, 58.5 cm frame, and have done about 6 conversions of bikes 57-62 cm size range. In all cases, regardless of trail / fork rake, going with 650b tires created more room between fender and toe. It also allowed the Q-factor to remain narrow, while accommodating the wider (up to 42mm) tire, plus fender, and keeping the chainstays shorter than 46 cm.

In terms of ride “feel”, there isn’t much difference for smooth roads, but I do feel like I need a few more mm of width on 650b to smooth out the bumps. Lowering the pressure helps quite a bit though, so having a fatter tire that won’t bottom out on dirt road potholes is an added bonus.

[NHAero]

Thanks, helpful.
If I had a frame built, or bought one used, I'd opt for clearance for at least 42mm and fenders. I rode the Anderson with the road 37mm tires on D2R2 without wishing for more tire in all but a couple of spots, so that's where I've settled for now for this type of bike. It fits nicely between the Firefly with 25mm tires that plump to 27+ on wide rims, and the Litespeed dropbar with 55mm file tread tires.

Originally Posted by Pastashop

I’ve one bike designed for 650x38xFenders, 58.5 cm frame, and have done about 6 conversions of bikes 57-62 cm size range. In all cases, regardless of trail / fork rake, going with 650b tires created more room between fender and toe. It also allowed the Q-factor to remain narrow, while accommodating the wider (up to 42mm) tire, plus fender, and keeping the chainstays shorter than 46 cm.

In terms of ride “feel”, there isn’t much difference for smooth roads, but I do feel like I need a few more mm of width on 650b to smooth out the bumps. Lowering the pressure helps quite a bit though, so having a fatter tire that won’t bottom out on dirt road potholes is an added bonus.

[NHAero]

I wonder what the chainstay length and front center dimensions are on that Firefly posted earlier in the thread.

[palincss]

Originally Posted by happycampyer

650b x 37 is a pretty small tire—the OD is shorter than a 700c x 23mm tire, and it sort of defeats the purpose of going for 650b.

I'm not sure where you'll find 650Bx37 - the usual sizes are 38 and 42mm. A 38mm tire is 1 1/2" wide. Compared to a 23mm or even a 28mm tire, it's an amazing, almost shocking difference. Broken pavement, chipseal, even gravel are all much, much nicer.

Yes, a 42 mm tire is even more plush. A bit. But certainly not the night-and-day difference between 700Cx28 and 650Bx38.

The purpose of going 650B is to get a wider tire. Compared to 23mm, 38mm is definitely wider. "Defeats the purpose"? I don't think so.



This Weigle Randonneur has 650Bx38 Loup Loup Pass tires.